The glorious past of Catholic Europe and the technological sophistication of the future are merging in a project of unprecedented scope funded by the European Commission. 

Through its Horizon Research and Innovation grant, the commission has allocated no less than 3 million euros to the Repertorium project, which aims to develop artificial intelligence (AI) tools to help preserve the Old Continent’s musical heritage by digitizing hundreds of thousands of medieval musical manuscripts. These tools will subsequently give rise to new immersive listening experiences for classical works.

This initiative is an extension of Neumz, the large Gregorian chant recording project developed between 2019 and 2022 and that made available the entire liturgy of the Novus Ordo through a smartphone app. 

Repertorium, which will further secure this distinctly Christian heritage by enabling some 2 million chants to be sorted, met the criteria required by the commission for this funding, namely those of “reviving, valorizing and fostering traditional crafts techniques and combining them with new and emerging cutting-edge technologies.”

The project, which began in January 2023 and is due to run for three years, will also deliver online access to the entire traditional Latin liturgy, thanks to a partnership with the Monastery of Le Barroux, in southern France.

Teaching Music to Artificial Intelligence 

At the intersection of preserving cultural heritage and promoting technological innovation, Repertorium will serve the Catholic tradition of Gregorian chant on a number of levels. 

As with Neumz, it all began with the Benedictine Abbey of Solesmes, in northeastern France, considered the center of Gregorian chant since the vast manuscript-collecting operation was launched by the community’s monks across Europe in the 19th century. Their archive of almost 400,000 photographs of musical manuscripts, which supplies the world’s Catholic communities with chants for the Novus Ordo and traditional Latin rites, is now being protected from the ravages of time and potential disaster by the creation of a digital backup that will remain accessible to musicologists worldwide through Oxford’s DIAMM portal.

The second step is to index and catalogue the 2 million or so chants contained in these archives. This is where AI comes in. 

“Ninety-nine percent of these songs have duplicates and are present on different manuscripts, yet it takes about three minutes for an expert to identify a song and catalog it,” John Anderson, founder of Neumz and one of the main coordinators of the Repertorium consortium, told the Register. “According to our calculations, an expert alone would need 500 years to index everything, which is preposterous, and we can’t employ 500 people to do the job, so AI will give us a hand.”

The Universities of Alicante and Jaén in Spain, among the 13 organizations and institutions involved in the project, are in charge of developing an optical music recognition and music information retrieval algorithm that will analyze the entire archive and compare it with other external databases such as the Cantus Index network. 

Based on nearly 8,000 hours of audio files supplied by the Neumz App and its developer Odratek, the AI is being gradually trained to listen to music and follow scores. Similarly, a total of 127,000 songs will first be manually indexed, to help AI develop music information retrieval functions.

The AI system designed by Repertorium — which will be able to read scores, follow audio and recognize the sounds of individual instruments — will then be extended to other types of music will then be extended to other types of music, including classical music concerts, offering immersive experiences where it will be possible to follow the performance in the form of an “acoustic hologram,” or to mute and solo instruments in the orchestra.

Forgotten for 1,000 Years 

The work of eliminating duplicates provided by music information retrieval technology should enable more than 90% of the songs in the Solesmes archives to be identified and catalogued within three years, according to Anderson. This will enable experts to save precious time and concentrate on the unidentified works. 

“While chants are being cataloged, new work are also constantly being discovered,” Anderson continued, adding that chants not matching any Cantus ID number will be passed on to the Spanish Gregorian chant research group, Schola Antiqua, which will be able to authenticate unpublished pieces. 

The project coordinators already estimate that some 4,000 new chants are expected to be unearthed from the archives. They will be released to the public on the occasion of concerts in Europe at the end of the work. “We have in mind to organize traditional concerts where the audience will discover Gregorian chants, some of whose melodies have not been heard for 1,000 years,” Anderson said.

One of the much-anticipated aspects of the project for Catholics worldwide is the recording and online distribution of the complete Tridentine liturgy. This option is made possible by the French Abbey of Sainte Madeleine du Barroux, a symbol of the monastic renewal in Europe, which has unusually opened its doors to the Neumz team as part of the Repertorium project. Over a period of a little more than a year, some 2,200 hours of Gregorian chants sung during Mass and Divine Office in the Tridentine forms, according to the ancient manuscript tradition, will be recorded and made available to Neumz subscribers, with translations of the Latin texts in 5 languages and the scores in synchronized square notation, the historical and most widely used musical notation system in Gregorian chant. 

Until now, the application has only provided the chants of the Novus Ordo — the Mass of Paul VI — recorded at the Abbey of Notre-Dame de Fidélité in Jouques (some 60 miles from Le Barroux). It will now be possible to select the rite of one’s choice from the smartphone app. 

“There is a huge demand from our subscribers for the Vetus Ordo Rite [the liturgy existing before Vatican II], especially in the U.S., and this European initiative offered the perfect opportunity to provide this service, then preserving and disseminating a highly valuable part of our historic heritage,” Anderson said.

‘Thirsting for Prayer’ 

His ambition since the conception of Neumz, that is culminating in Repertorium, is to reintroduce Gregorian chant to churches on a massive scale, particularly in view of the growing ignorance of this tradition, even among priests. By facilitating access to all the chants classified by office, he hopes to popularize them. 

For the communities of Jouques and Le Barroux, the evangelizing potential of such an initiative was well worth the “intrusion” of microphones, whose installation came to disturb the monastic tranquility of their offices. 

“We’re clearly seeing a growing attraction to Gregorian chant among young people, including our younger sisters, who often don’t come from traditionalist backgrounds, but who, having tasted this tradition, have the impression of joining a chain that began centuries and centuries ago,” Benedictine Sister Marie-Dorothée, who is responsible for recording the chants at Jouques, told the Register, pointing out that chants in vernacular languages have more difficulty withstanding the passage of fashions and generations. 

“By singing melodies sung identically by monks in the 12th century, one has the feeling of aggregating to a single prayer that rises to God through time and space, and this brings great inner wholeness,” she added, underlining the extraordinary unifying power of this practice at a time when Western secularization can weaken the unity of the Church. “All over the world, people in search of nourishment for the soul and thirsting for prayer come to cling to this wagon of Gregorian chant that leads them to God, and it is this desire to facilitate such transmission that has led us to welcome this project within the walls of our abbey.”